Apparatus for conveying sheets through a printing machine

Abstract

An apparatus for conveying sheets from a printing machine to a stack has highly rigid gripper bars that can be produced with relatively little expense, and the gripper assembly permits great flexibility in the use of the apparatus. The apparatus has at least one gripper bar carrying one or more grippers which, during the conveyance, holds a sheet at its edge between a gripper finger and a gripper pad. Endless chains move the gripper bar on a path between a cylinder belonging to the machine and the stack. An actuating mechanism opens and closes the gripper as a sheet is picked up from the cylinder and as it is allowed to fall onto the stack. In the opened state, the gripper finger is located below a path described by the upper edge of the gripper pad.

1. An apparatus for conveying sheets from a printing machine to a stack, comprising:
 gripper bar carrying at least one gripper having a gripper finger and a gripper pad for holding a sheet at an edge thereof between said gripper finger and said gripper pad during a conveyance of the sheet; 
 an endless chain for moving said gripper bar on a path between a cylinder of the printing machine and the stack; and 
 an actuating mechanism configured to close and open said gripper as a sheet is picked up from the cylinder and as the sheet is released at the stack; 
 in an open state of said gripper, said gripper pad defining an upper edge and said gripper finger lying below a path described by said upper edge of said gripper pad; 
 said gripper bar having a hollow profile and a gripper shaft rotatably disposed in an interior of said hollow profile and being rotational to and fro within a angle range, a multiplicity of gripper fingers for holding the trailing edge of the sheet being affixed to said gripper shaft, and said gripper fingers each projecting through a respective opening formed in said hollow profile, said opening having a width, in a direction of rotation of said gripper fingers, being less than a range of movement of said gripper fingers in the rotational angle range. 
 
     
     
       2. The apparatus according to  claim 1 , wherein said gripper finger is an angled finger having a limb with an arcuate form in the rotational angle range. 
     
     
       3. The apparatus according to  claim 2 , wherein said gripper bar has an external contour in cross section, and said limb is matched to said external contour of said gripper bar. 
     
     
       4. The apparatus according to  claim 2 , wherein, in the opened position, said limb of said gripper finger is disposed in an interior of said gripper bar. 
     
     
       5. The apparatus according to  claim 1 , wherein said gripper bar is formed of a drawn hollow profile. 
     
     
       6. The apparatus according to  claim 1 , wherein said opening is a clearance for a mounting tool for fixing said gripper finger to said gripper shaft. 
     
     
       7. The apparatus according to  claim 1 , wherein said gripper fingers are elastically sprung. 
     
     
       8. The apparatus according to  claim 1 , wherein said gripper shaft is a thin-walled tube. 
     
     
       9. The apparatus according to  claim 1 , wherein said at least one gripper is one of a plurality of grippers formed as trailing edge grippers.